What is the Fifth Age?

Sorry for bombarding the newsgroup with questions! Last one for now!

I've been reading DL books for a while and I recently re-read the 
Chronicles for old times sake (and they are still as good as they were 
when I was little!). I decided not to re-read Legends because I remember 
not enjoying them as much as the Chronicles, probably because the story 
is much more singular and doesn't involve all the Companions. At any 
rate, I know the overall story of what happened with Raistlin so I moved 
on to The Second Generation (then I plan to do DoSF and the War of Souls 
Trilogy).

But my question now is, what exactly is the Fifth Age and why do so many 
people hate it? Does it involve the War of Souls or can it be something 
completely ignored?

And please, don't give any spoilers beyond the Legends trilogy, because 
I haven't read past that yet (aside from a bunch of other random DL 
novels that are unrelated to the main storyline of the Companions and 
their children).